In 1976, Professor, Kaminsky reported that the polymerization of olefin can use zirconocene dichloride compound as catalyst and methyl aluminoxane (MAO) compound obtained by a partial hydrolysis of trimethyl aluminium as co-catalyst (A. Anderson, J. G. Corde, J. Herwig, W. Kaminsky, A. Merck, R. Mottweiler, J. Pein, H. Sinn, and H. J. Vollmer, Angew. Chem. Int. Ed. Engl., 15, 630, 1976).
Since then, Exon filed the patent (U.S. Pat. No. 5,324,800) about the polymerization of olefin using a metallocene compound having various substituents at cyclopentadienyl ligand.
Since the above metallocene catalyst has uniform active sites, there are the advantages such that the molecular weight distribution of polymer is narrow, the co-polymerization is easy, the distribution of second monomer is uniform, and also the polymer stereostructure can be controlled according to the symmetry of catalyst in the case of the polymerization of propylene. Specifically, the existed Ziegler-Natta catalyst can produce only isotactic polypropylene, but in the case of using metallocene catalyst, various polypropylene, such as isotactic, syndiotactic, atactic, and also hemiisotactic polypropylene, and the like, can be stereo-regularly produced. For example, in the case of syndiotactic polypropylene synthesized by using metallocene, there are characteristics such that it has a low crystallinity, the suitable stiffness and hardness, a good transparency, and also a high impact resistance. That is, the active researches are currently underway regarding the metallocene catalyst because there are advantages such that the stereo-structure can be controlled by using the metallocene catalyst on preparing polyolefin, and also the properties of polymer can be easily controlled. However, there is a problem such that for the polymerization technique of olefin using the above homogenous catalyst, the shape of polymer is difficulty maintained in the case of a gas-phase process or a slurry process, and also a large quantity of MAO is required for expressing a maximum activity of metallocene catalyst. The metallocene catalyst should be used after supporting in a suitable support in order to solve the above problem. In addition, there are advantages such that in the case of supporting the catalyst as mentioned above, the weight distribution can be controlled according to the usage, the apparent density of the polymer produced can be improved, and also the fouling phenomenon in the reactor can be decreased, as well as the shape of the polymer produced can be controlled.
A method for preparing supported metallocene catalyst by contacting with aluminoxane after firstly combining physicochemically a metallocene compound with a support; a method for preparing supported metallocene catalyst by reacting with the metallocene compound after supporting aluminoxane in a support; a method for preparing supported metallocene catalyst by supporting in a support after firstly contacting aluminoxane with the metallocene compound; and the like are generally known as a method for preparing supported metallocene catalyst. The catalyst structure having single active site should be maintained after supporting so that the supported catalyst has the same high-activity and co-polymerization efficiency with the homogeneous catalyst. In addition, the catalyst should not be removed from the support on polymerizing in order to prevent a fouling in a reactor. In addition, the fineness, the fineness distribution and the apparent density of the polymer are depended on a particle shape and a mechanical property of the supported catalyst. Korean Registration Publication No. 10-0404780 discloses a metallocene compound having silacycloalkyl substituent, and a supported catalyst using the same, but in the case of using the above metallocene compound in a gas-phase process or a slurry process, since the catalyst is isolated from a support, a fouling may be occurred in a reactor.
Meanwhile, Japan Registration Publication 1994-56928 discloses a method for preparing supported metallocene catalyst by combining metal at the ligand after firstly supporting ligand on a surface of support by a chemical bond. However, there is a disadvantage such that the process for preparing catalyst is very complicated, and a lot of catalysts should be supported on the support.
It is the oldest method for preparing non-homogeneous catalyst having a single active site; comprising reacting with the metallocene compound after supporting aluminoxane at the support among the above various methods for preparing supported catalyst. For example, the supported catalyst is prepared by reacting silica with aluminoxane solution; filtering filtrate out; and then reacting with zirconocene dissolved in toluene or aliphatic hydrocarbon solution, and the supported catalyst can be used in polymerization or co-polymerization in a gas-phase process or a slurry process. The method for supporting has a relative high activity because co-catalyst is physicochemically fixed on the surface of support and the catalyst is existed as a type of the combination with the co-catalyst by an ionic bond. In addition, the method for supporting can be easily applied in an existed slurry process or gas-phase process because the single-phase catalyst can be prepared, in which it is not required to further use aluminoxane in a polymerization reactor. However, there were disadvantages such that the fouling in a reactor may be occurred because the isolation of catalyst cannot be completely prevented, and there is a limit to aluminoxane that can be combined to silica so that there is a limit to the metallocene compound that can be combined by that.
International Patent Publication No. WO2002/040549 discloses olefin polymerization catalyst including a support, an ionization active agent, such as dimethylanilinium tetra (pentafluorophenyl)borate, triphenylcarbeniumtetra(pentafluorophenyl)borate, and the like, and an supported active agent, such as a metallocene compound, MAO, and the like; Japan Publication Patent No. 2008-121027 discloses the catalyst for preparing olefin polymer, including a support, such as silica, a transition metal compound, such as methylaluminoxane, bis(indenyl)zirconiumdichloride, and the like, and [PhNMe2H] [B(C6F5)4]; US Publication Patent No. 2006/0116490 discloses metallocene catalyst for polymerizing olefin, including a metallocene compound and co-catalyst that is combined of an ionic compound, such as aluminoxane, tetrakis(pentafluorophenyl) borate, and the like, and a support; and Akihiro Yano discloses an ethylene polymerization catalyst including a metallocene compound and dimethylanilinium tetrakis(pentafluorophenyl)borate (Me2PhNH.B(C6F5)4/triisobutylaluminum (i-Bu3Al) in Journal of Molecular Catalysis A; Chemical 156_2000.133-141. However, there are disadvantages such that the above catalysts have a low activity and the molecular weight distribution cannot be easily controlled.